1. Flame lenght & diameter
Note on the thereon mentioned formulas and data:
Formulas refer to burner output (not to boiler nominal output)
Burner output refers to N.C.V. (net calorific value)
US formulas, on the other hand, refer to G.C.V. (gross calorific value)
On test boilers, only diameter up to 800 mm are normalized
F.I. (firing intensity) heavily influences NOx emissions: the lower the F.I., the lower the emissions
Diameter value formulas are semi-empirical (not included in ISO and EN norms)

2. TEST BOILER (According to EN676 - EN267)
Flame lenght & diameter
TEST BOILER (According to EN676 - EN267) L D
Normalized diameters

3. COMMERCIAL BOILER (direct pass type)
Flame lenght & diameter
COMMERCIAL BOILER (direct pass type) L D
Flame reversing back chamber
Firing intensity
(Vcc combustion chamber volume)

4. COMMERCIAL BOILER (“Reversed flame” type)
Flame lenght & diameter
COMMERCIAL BOILER (“Reversed flame” type) L D
Firing intensity
(Vcc combustion chamber volume)

5. U.S. COMMERCIAL BOILER (direct pass type)
Flame lenght & diameter
U.S. COMMERCIAL BOILER (direct pass type) L D
Flame reversing back chamber
Firing intensity
(Vcc combustion chamber volume)

6. U.S. COMMERCIAL BOILER (“Reverse flame” type)
Flame lenght & diameter
U.S. COMMERCIAL BOILER (“Reverse flame” type) L D